The interaction between poly(ethylene glycols) and proteins will be studied. The effects of poly(ethylene glycols) of different sizes on the thermal denaturation of proteins will be monitored yielding the basic thermodynamics parameters of protein unfolding. The effects of solvents on the kinetics of thermal denaturation will also be investigated. Combining the results on the thermodynamic and kinetic studies of protein thermal denaturation as a function of poly(ethylene glycols), it enables a thorough characterization of the energy profile of these proteins in these solvents. The polymorphic nature of brain tubulin will be studied by isoelectric focusing as a function of protein and ampholyte concentrations. The individual subspecies will be isolated and the nature of such heterogeneity will be investigated by peptide mapping.